I've recently been looking at what makes chords what, and hence my first target for this was looking at major, minor, sus2, and sus4 chords. I know major chords are made up of the first, the third, and the fifth of the scale, and from memory I think that minor chords are the same as major chords, apart from the interval to the third is a minor third (hence the resultant chord has it's third of the scale one semitone flattened).

Suspended chords (sus2 and sus4) however are arousing a bit of confusion from my end. I can see that in sus2 chords the third is brought down to the second, and in sus4 chords that the third is brought up to the fourth. Presumably this would explain the '2' and '4' in the name - but that leaves me questioning the 'sus' portion of their name.

What's up with the 'sus' in the name of sus2 and sus4 chords?

EDIT: Removed some text about a possible link to "suspended" intervals (which as far as I'm aware don't actually exist - I was thinking about diminished intervals).

Worth noting is that the note changes name in a sus chord and not in an aug chord (Csus compared to C has an F instead of E. Caug compared to C has a G# instead of a G, but it is still a G). The difference is changing a note to another, versus giving an alteration to one of the tones.
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GauthierApr 16 '12 at 7:02

This is not my point. My point is that in a sus chord, the third is replaced by the fourth. In an aug chord, the fifth is modified (not replaced) but is still a kind of fifth.
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GauthierJun 10 '12 at 14:42

2 Answers
2

The term comes from traditional music theory, and it refers to that the chord has a note that was suspended, or 'delayed', or 'carried over', from the previous chord. Traditionally the suspended fourth note in the sus4-chord should also be resolved to the third before any further chord action.

Here is an example chord progression (with notes from bottom up including the bass line) illustrating a suspension with resolution:

F (F-A-C-F), Csus4 (C-G-C-F), C (C-G-C-E), F (F-A-C-F)

Or:

The top F of the first chord (F) is suspended into the second chord (Csus4), and then resolved in the third chord (C) before we go ahead with the fourth chord (F).
(If you ignore the bottom bass note you will find that the chords in the example are in inversions.)

However in many modern music styles the "suspended" note does not need to be prepared from the previous chord, nor does it have to be resolved. Thus sus chords have become chords in their own right, not depending on its surroundings. In this modern context the term 'suspended' might seem odd.

Scales can't have steps suspended; they can be diminished or augmented. Every step in a scale - hence also a chord - can be either of those. An augmented chord is two major thirds, a diminished chord is two minor thirds.

Sus means that you make a suspension by introducing a tension note.

Sus2 and 4 chords differ from the usual chords by thirds in that they are essentially chords by fourth. Take the note G and go a fourth up to C and another fourth up to F. Essentially you have the outline of a G7sus4 but that's not the point. If you put the G up an octave you have a Csus4. Put the C up an octave and you get Fsus2.

I can put the G up the G-major scale to C, then a C up the C-major scale to F, but I get confused when you say "Essentially you have the outline of a G7sus4". You mean these three notes would make up a G7sus4 - why is this? Then you start talking about things being an octave up which completely throws me off - anything an octave up is surely itself? G and octave up is G, C and octave up is C.
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joesavageApr 15 '12 at 9:15

G C F is an outline of G7sus4 in that it only needs the fifth (D). Putting things octaves up or down they will still be the same but the chords will be inverted. Just because we start on G doesn't mean that you should think in G-major, this example is purely in C-major
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Thomas BrylaApr 15 '12 at 9:18

Have you tried playing these inversions on a piano?
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Thomas BrylaApr 15 '12 at 9:19